This invention relates to an operating head for automatic machine tools with a projecting interchangeable chuck unit.
In particular, the head in accordance with the invention comprises a support that rotates around a first axis, which said support incorporates a power transmission system, and a kinematic mechanism for angular positioning of the chuck unit around a second axis, usually orthogonal to the axis of rotation of the support.
A plate integral with the chuck assembly is fitted with couplings designed for the connection of the said support.
The chuck assembly incorporates a power unit or motorised chuck suitable to perform high-speed finishing tasks.
This characteristic allows the operator to change over from roughing to finishing tasks without replacing the entire head (as is necessary with known equipment in which the chuck assembly is mounted on a fork support), merely by replacing the chuck unit, a much quicker and cheaper operation.
The automatic machine tools used to perform chip-forming tasks such as milling, contouring, etc., comprise a support that moves along three orthogonal axes on which an operating head with two degrees of freedom is mounted; the said operating head carries a tool unit consisting, for example, of a chuck or motorised chuck, on which the tool required for each task is mounted.
The structure and characteristics of these operating heads vary considerably, depending on whether the job in hand is a high-power task, performed with a roughing tool which rotates at a relatively low speed (max. 3000-5000 rpm) and removes large amounts of material, consequently discharging considerable reactive forces onto the structure, or a finishing/milling task, performed with a tool which rotates at high speed (up to 15,000-30,000 rpm).
The stresses to which the tool is subjected during these various types of work, which are discharged onto the structure and the upstream devices, require the use of chucks with different characteristics and dimensions, which means that different operating heads have to be manufactured.
In accordance with the present state of the art, when the operator wishes to change over from a high-power task to a finishing task, the entire operating head must be replaced, involving very high costs.
These factors lead to an increase in overall costs, due not only to the longer production times but also to the need to have two or more operating heads complete with the corresponding kinematic mechanisms, if not two or more separate machines used for roughing, finishing or other complementary tasks.
This problem is solved by the present invention, which relates to an operating head for automatic machine tools that includes an interchangeable chuck unit fitted to project from a support, which said unit can be replaced quickly and easily with a chuck of different characteristics.
For example, as the power transmission system and angular positioning devices of the chuck are built into the support to which the chuck unit is fitted, the operator can switch from a power chuck to a medium- or high-speed motorised finishing chuck very quickly, with no need to replace the entire head.